1. Technical Field
The present invention relates to apparatus and methods for conveying particulate material and, in particular, to apparatus and methods for feeding and metering particulate material. More particularly, the present invention relates to apparatus and methods for feeding and metering particulate material which are capable of adjustment to accommodate a range of different particulate materials.
2. Background Information
The transportation and movement of particulate materials such as sugar, breakfast cereal, dog food, and the like, presents special problems inasmuch as such materials often display different static characteristics.
U.S. Pat. No. 4,163,489 to Wahl discloses a feeder apparatus in which bulk materials, in fibrous or stringy form, is delivered onto an endless belt by means of a rotating rake. The weight of the material on the belt is sensed by a transducer which effects the operation of a control system for automatically adjusting the belt speed to maintain a constant discharge of the material from an end of the belt. Excess material deposited on the belt is returned to the hopper by the rotating rake.
U.S. Pat. No. 5,485,909 to Hay discloses an apparatus for transporting and metering particulate material including a transport channel having an inlet and an outlet. The transport channel is formed between substantially opposed faces of first and second rotary disks movable between the inlet and outlet towards the outlet and at least one arcuate wall extending between the inlet and outlet. The apparatus further includes a device provided adjacent the inlet for preventing a dead area from being formed to thereby provide a constant and uniform flow of the particulate solids within the apparatus.
A need still exists for an apparatus and method for feeding and metering particulate material which affords a simple and inexpensive way to adjust operation of the apparatus and method based on differences in characteristics between different types of particulate materials.
It is an object of the present invention to provide an apparatus and method for feeding and metering particulate material in which an easy and inexpensive means for adjustment is provided based on differences in characteristics between different types of particulate materials.
It is another object of the present invention to provide an easy, inexpensive and effective means of sealing the lower edge of a particulate material sealing plate against a surface, and particularly against a curved surface.
It is still another object of the present invention to provide an easy, inexpensive and effective means of sealing a rotating shaft, and particularly for sealing a rotating shaft having a cylindrical member mounted thereon.
The present invention is an apparatus for feeding a particulate material. There is a drum having a peripheral surface and a central axis which is rotatable about its central axis. There is a first particulate material retaining wall which has an inner and outer edge. This wall is positioned such that said outer edge is remote from the peripheral surface of the drum and the inner edge is adjacent the peripheral surface of the drum. The inner edge is moveable from said peripheral surface of said drum. A second particulate material retaining wall having an inner and outer end and positioned such that said outer end is remote from the peripheral surface of the drum. The first particulate retaining wall is preferably spaced from the peripheral surface of the drum by a distance which corresponds to the angle of repose of the particulate material being used.
Also encompassed by the present invention is an apparatus for feeding a particulate material which includes a rotatable drum having a direction of rotation, a peripheral surface having an upper side and a longitudinal axis, and having a generally conically shaped body of particulate material positioned on said upper side of the peripheral surface. The conically shaped body of particulate material having an apex and base, a sloped side and having a forward side in the direction of rotation of the drum and an opposed rearward side. There is also a first particulate material retaining means having an inner edge and an outer edge. This first particulate retaining means is positioned such that said inner edge of said first particulate retaining means is spaced from the peripheral surface of the drum by a distance sufficient so that said inner edge is positioned approximately on the front sloped side of the conically sloped body of particulate material. There is also a second particulate material retaining means having an inner edge and an outer edge. The second particulate material retaining means is positioned such that said inner edge of said second particulate material retaining means is adjacent the peripheral surface of the drum and said second particulate material retaining means is positioned in rearward relation to the apex of the conically sloped body of particulate material.
Also encompassed by the present invention is an apparatus for feeding a particulate material which includes a generally cylindrical drum having a peripheral surface having an upper side and a longitudinal axis. There is a body of a particulate material positioned on said upper side of said peripheral surface. This body of particulate material has a surface with a center point and a sloped line extending from said center point which is tangent to the peripheral surface of the drum or a parallel to a line which is tangent to the peripheral surface of the drum. There is also a horizontal line tangent to the peripheral surface of the drum which forms with the sloped line an acute angle. The particulate material has a characteristic angle of repose which is approximately equal to this acute angle. There is also a first particulate material retaining means having an inner edge and an outer edge. This first particulate material retaining means is positioned such that said inner edge of said first particulate retaining means is spaced from the peripheral surface of the drum by a distance sufficient so that this inner edge is positioned approximately on the sloped line extending from said center point of the surface of the particulate material which is tangent to the peripheral surface of the drum. This is also a second particulate material retaining means positioned adjacent the body of particulate material in opposed relation to the first particulate material retaining means. Means are also provided for rotating the drum about its longitudinal axis in a direction from the center point of the surface of the center point of the surface of the particulate material toward the first particulate material retaining means.
The present invention also encompasses a method for feeding a particulate material. A rotatable drum which has a direction of rotation, a peripheral surface having an upper side and a longitudinal axis, is provided. A conically shaped body of particulate material is positioned on said upper side of the peripheral surface, and this conically shaped body of particulate material having an apex and base, a sloped side and having a forward side in the direction of rotation of the drum and an opposed rearward side. A first particulate material retaining means having an inner edge and an outer edge is provided. The inner edge of said first particulate retaining means is spaced from the peripheral surface of the drum by a distance sufficient so that said inner edge is positioned approximately on the front sloped side of the conically sloped body of particulate material. A second particulate material retaining means having an inner edge and an outer edge provided and positioned such that said inner edge of said second particulate material retaining means is adjacent the peripheral surface of the drum and is positioned in no rearward relation to the apex of the conically sloped body of particulate material. The drum is then rotated about its longitudinal axis in the direction of rotation.
Also encompassed by the present invention is a structure and method for sealing a lateral plate at least partially surrounding a body of a particulate material. The particulate material. The particulate material is superimposed on a base surface. The lateral plate is seated on the base surface on the rear corner between its inner edge and rear surface. The inner edge of the lateral plate is angularly disposed to the base surface by an angle which is approximately equal to the angle of repose of the particulate material.
The present invention also encompasses a seal for a rotatable on which a cylindrical member is mounted. Adjacent the ends of the rotatable shaft there is a stationary seal wall which is cross sectionally curved preferably the wall has a repeating curved pattern such as a sinusoidal pattern.